[0001] The present invention relates generally to the modulation of the growth of collateral
arteries or other arteries from preexisting arteriolar connections. In particular,
the present invention provides a method for enhancing the growth of collateral arteries
and/or other arteries from preexisting arteriolar connections comprising contacting
tissue or cells with a monocyte chemotactic protein (MCP) or a nucleic acid molecule
encoding said MCP. The present invention also relates to the use of an MCP or a nucleic
acid molecule encoding said MCP for the preparation of pharmaceutical compositions
for enhancing collateral growth of collateral arteries and/or other arteries from
preexisting arteriolar connections. Furthermore, the present invention relates to
a method for the treatment of tumors comprising contacting tissue or cells with an
agent which suppresses the growth of collateral arteries and/or other arteries from
preexisting arteriolar connections through the attraction of monocytes. The present
invention further involves the use of an agent which suppresses the growth of collateral
arteries and/or other arteries from preexisting arteriolar connections through the
attraction of monocytes for the preparation of pharmaceutical compositions for the
treatment of tumors.
[0002] In the treatment of subjects with arterial occlusive diseases most of the current
treatment strategies aim at ameliorating their effects. The only curative approaches
involve angioplasty (balloon dilatation) or bypassing surgery. The former carries
a high risk of restenosis and can only be performed in certain arterial occlusive
diseases, like ischemic heart disease. The latter is invasive and also restricted
to certain kinds of arterial occlusive diseases. There is no established treatment
for the enhancement of collateral growth.
[0003] Vascular growth in adult organisms proceeds via two distinct mechanisms, sprouting
of capillaries (angiogenesis) and in situ enlargement of preexisting arteriolar connections
into true collateral arteries
1. Recent studies have disclosed mechanisms leading to angiogenesis with vascular endothelial
growth factor (VEGF) as a major component
2-6. This specific endothelial mitogen is upregulated by hypoxia and is able to promote
vessel growth when infused into rabbit hindlimbs after femoral artery excision
7,8. These studies however did not distinguish between capillary sprouting, a mechanism
called angiogenesis, and true collateral artery growth. Whereas VEGF is only mitogenic
for endothelial cells, collateral artery growth requires the proliferation of endothelial
and smooth muscle cells and pronounced remodeling processes occur
1,9-12. Furthermore mainly capillary sprouting is observed in ischemic territories for example
in the pig heart or in rapidly growing tumors
1,3,13,14. True collateral artery growth, however, is temporally and spacially dissociated
from ischemia in most models studied
1,15. Other or additional mechanisms as those described for angiogenesis in ischemic territories
are therefore needed to explain collateral artery growth. From previous studies it
is known that these collateral arteries grow from preexisting arteriolar connections
1.
However, while agents such as VEGF and other growth factors are presently being employed
to stimulate the development of angiogenesis after arterial occlusion, such agents
are not envisaged as being capable of modulating the growth of preexisting arteriolar
connections into true collateral arteries.
[0004] Thus, the technical problem of the present invention is to provide pharmaceutical
compositions and methods for the modulation of the growth of collateral arteries and/or
other arteries from preexisting arteriolar connections.
The solution to this technical problem is achieved by providing the embodiments characterized
in the claims.
[0005] Accordingly, the invention relates to a method for enhancing the growth of collateral
arteries and/or other arteries from preexisting arteriolar connections comprising
contacting tissue or cells with a monocyte chemotactic protein (MCP) or a nucleic
acid molecule encoding said MCP.
[0006] For the purpose of the present invention the growth of arteries from preexisting
arteriolar connections is also called "arteriogenesis". In particular, "arteriogenesis"
is the in situ growth of arteries by proliferation of endothelial and smooth muscle
cells from preexisting arteriolar connections supplying blood to ischemic tissue,
tumor or sites of inflammation. These vessels largely grow outside the affected tissue
but are much more important for the delivery of nutrients to the ischemic territory,
the tumor or the site of inflammation than capillaries sprouting in the diseased tissue
by angiogenic processes.
In the context of the present invention the term "monocyte chemotactic protein" or
"'MCP" refers to proteins and peptides which can act on monocytes and lead to augmentation
of monocyte activation accumulation and migration
35. Thus, according to the present invention, any MCP or other substances which are
functionally equivalent to an MCP, namely which are capable of activating and attracting
monocytes can be used for the purpose of the present invention. The action of the
MCPs employed in the present invention may not be limited to the above-described specificity
but they may also act on, for example eosinophils, lymphocyte subpopulations and/or
stem cells.
[0007] In accordance with the present invention, it has been found that through the attraction
of monocytes by monocyte chemotactic protein-1 (MCP-1) the growth of collateral arteries
and arteriogenesis could be significantly enhanced in animals after femoral artery
occlusion. Experiments performed within the scope of the present invention demonstrate
that local infusion of MCP-1 increases both collateral- and peripheral conductance
after femoral artery occlusion due to enhanced vessel growth by augmentation of monocyte
accumulation concomitant with proliferative effects on endothelial and/or smooth muscle
cells. Thus, MCPs or nucleic acid molecules encoding MCPs can be used to attract monocytes
to a certain tissue or cell which in turn leads to growth of collateral arteries as
well as to growth of arteries from preexisting arteriolar connections, which is needed
for the cure of several occlusive diseases.
MCP-1 is a 14-kDa glycoprotein secreted by many cells, including vascular smooth muscle-
and endothelial cells
29-32 and induces monocyte chemotaxis at subnanomolar concentrations
33. MCP-1 is a potent agonist for the β chemokine receptors CCR 2 and CCR 4 which are
both mainly expressed by monocytes but also have been found to be present on basophils,
T- and B-lymphocytes
34. These G-protein coupled seven-transmembrane-domain receptors lead to the activation
of monocytes and increased adhesiveness of integrins, a process which finally leads
to monocyte arrest on endothelial cells
35. The MCP-1 gene shows large interspecies homologies
30 and can be induced by various cytokines (e.g. Tumor necrosis factor α) and immunoglobulin
G
36. Recently it has been shown in vitro that gene expression and protein secretion of
MCP-1 are also upregulated by shear stress and cyclic strain
16-18. These mechanical forces have recently been shown to increase monocyte chemotactic
protein-1 (MCP-1) secretion in cultured human endothelial cells leading to increased
monocyte adhesion
16-18. These findings complement the observation that monocytes adhere and migrate into
the vessel wall of collateral arteries after induction of coronary artery stenosis
in the dog heart at a time when the proliferation index is maximally increased
19. Furthermore, monocyte accumulation is also observed in the pig microembolization
model of angiogenesis
20. Moreover increased levels of MCP-1 mRNA were found in ischemic tissue of microembolized
porcine myocardium
21 as well as in reperfused ischemic myocardium
37. However, although there are several reports published that indicate that monocytes
are involved in angiogenesis
22-24 monocytes were not believed to play a role in the development of collateral arteries
and arteriogenesis
25.
[0008] The MCPs to be employed in the methods and uses of the present invention may be obtained
from various sources described in the prior art; see, e.g., Proösl
69, Dahinden
70, Alam
71 and Oppenheim
72. The potential exists, in the use of recombinant DNA technology, for the preparation
of various derivatives of MCPs comprising a functional part thereof or proteins which
are functionally equivalent to MCPs as described above. In this context, as used throughout
this specification "functional equivalent" or "functional part" of an MCP means a
protein having part or all of the primary structural conformation of an MCP possessing
at least the biological property of attracting monocytes. The functional part of said
protein or the functionally equivalent protein may be a derivative of an MCP by way
of amino acid deletion(s), substitution(s), insertion(s), addition(s) and/or replacement(s)
of the amino acid sequence, for example by means of site directed mutagenesis of the
underlying DNA. Recombinant DNA technology is well known to those skilled in the art
and described, for example, in Sambrook et al. (Molecular cloning; A Laboratory Manual,
Second Edition, Cold Spring Harbour Laboratory Press, Cold Spring Harbour NY (1989)).
For example, it was found that a mutation of the amino acids Leu25 and Val27 into
Tyr introduces a novel monocyte chemoattractant activity into interieukin-8, which
normally does not activate monocytes
66. MCPs or functional parts thereof or proteins which are functionally equivalent to
MCPs, may be produced by known conventional chemical syntheses or recombinant techniques
employing the amino acid and DNA sequences described in the prior art
69-72, for example, MCPs may be produced by culturing a suitable cell or cell line which
has been transformed with a DNA sequence encoding upon expression under the control
of regulatory sequences an MCP or a functional part thereof or a protein which is
functionally equivalent to MCP. Suitable techniques for the production of recombinant
proteins are described in, e.g., Sambrook, supra. Methods for constructing MCPs and
proteins as described above useful in the methods and uses of the present invention
by chemical synthetic means are also known to those of skill in the art.
[0009] In another embodiment, the invention relates to the use of a monocyte chemotactic
protein (MCP) or a nucleic acid molecule encoding said MCP for the preparation of
a pharmaceutical composition for enhancing collateral growth of collateral arteries
and/or other arteries from preexisting arteriolar connections.
The pharmaceutical composition comprises at least one MCP as defined above, and optionally
a pharmaceutically acceptable carrier or exipient. Examples of suitable pharmaceutical
carriers are well known in the art and include phosphate buffered saline solutions,
water, emulsions, such as oil/water emulsions, various types of wetting agents, sterile
solutions etc. Compositions comprising such carriers can be formulated by conventional
methods. The pharmaceutical compositions can be administered to the subject at a suitable
dose. The dosage regimen may be determined by the attending physician considering
the condition of the patient, the severity of the disease and other clinical factors.
Administration of the suitable compositions may be effected by different ways, e.g.
by intravenous, intraperitoneal, subcutaneous, intramuscular, topical or intradermal
administration.
[0010] In a preferred embodiment, said MCP used in the methods and uses of the invention
is selected from the group consisting of MCP-1, MCP-2, MCP-3, MCP-4, MIP-1α RANTES,
J-309 or any other CC-chemokine or classical chemoattractants like N-farnesyl peptides,
C5a, leukotriene B4 or Platelet-activating factor (PAF)
35,48.
[0011] In a particularly preferred embodiment, the method and uses of the invention are
for the treatment of subjects suffering from occlusive disease, preferably selected
from the group consisting of coronary artery diseases, cerebral occlusive diseases,
peripheral occlusive diseases, visceral occlusive diseases, renal artery disease and
mesenterial arterial insufficiency.
[0012] In a further preferred embodiment, the methods and uses of the invention are for
the treatment of subjects during or after exposure to an agent or radiation or surgical
treatment which damage or destroy arteries.
[0013] In a preferred embodiment, the MCP used in the methods and uses of the invention
is a recombinant MCP. DNA sequences encoding MCPs which can be used in the methods
and uses of the invention are described in the prior art, e.g., Garcia-Zepeda
34. Moreover, DNA and amino acid sequences of MCPs are available in the Gene Bank database.
As described above, methods for the production of recombinant proteins are well-known
to the person skilled in the art; see, e.g., Sambrook, supra.
[0014] In a further preferred embodiment, the pharmaceutical composition is designed for
administration in conjugation with growth factors, preferably fibroblast growth factor
or vascular endothelial growth factor (VEGF). This embodiment is particularly suited
for enhancing of both sprouting of capillaries (angiogenesis) and in situ enlargement
of preexisting arteriolar connections into true collateral arteries. Pharmaceutical
compositions comprising, for example, an MCP such as MCP-1, and a growth factor such
as VEGF may be used for the treatment of peripheral vascular diseases or coronary
artery disease.
[0015] In another preferred embodiment, the method of the invention comprises
(a) obtaining cells from a subject;
(b) introducing a nucleic acid molecule encoding the MCP into said cells, thereby
conferring expression and secretion of the MCP in a form -suitable for the attraction
of monocytes; and
(c) reintroducing the cells obtained in step (b) into the subject.
[0016] It is envisaged by the present invention that the MCPs and the nucleic acid molecules
encoding the MCPs are administered either alone or in combination, and optionally
together with a pharmaceutically acceptable carrier or exipient. Said nucleic acid
molecules may be stably integrated into the genome of the cell or may be maintained
in a form extrachromosomally. On the other hand, viral vectors may be used for transfecting
certain cells or tissues, preferably cells and tissue surrounding preexisting arteriolar
connections. Elements capable of targeting a nucleic acid molecule and/or protein
to specific cells are described in the prior art, for example Somia, Proc. Natl. Acad.
Sci., USA 92 (1995), 7570-7574. Thus, it is possible to employ the methods and uses
of the invention for somatic gene therapy, which is based on introducing of functional
genes into cells by ex vivo or in vivo techniques and which is one of the most important
applications of gene transfer; see, e.g., Schaper
73 and references cited therein.
[0017] Thus, in a preferred embodiment, the nucleic acid molecule comprised in the pharmaceutical
composition for the use of the invention is designed for the expression and secretion
of the MCP by cells in vivo in a form suitable for the attraction of monocytes by,
for example, direct introduction of said nucleic acid molecule or introduction of
a plasmid, a plasmid in liposomes, or a viral vector (e.g. adenoviral, retroviral)
containing said nucleic acid molecule.
[0018] As discussed above, the growth of arteries from preexisting arteriolar connections
is essential for the delivery of nutrition to tumors. Thus, if the growth of said
vessels to the tumor would be suppressed suppression and/or inhibition of tumor growth
is to be expected. Accordingly, the present invention also relates to a method for
the treatment of tumors comprising contacting tissue or cells with an agent which
suppresses the growth of collateral arteries and/or other arteries from preexisting
arteriolar connections through the attraction of monocytes. Agents which suppress
the growth of collateral arteries and/or other arteries from preexisting arteriolar
connections may be peptides, proteins, nucleic acids, antibodies, small organic compounds,
hormones, neural transmitters, peptidomimics, or PNAs (Milner, Nature Medicine 1 (1995),
879-880; Hupp, Cell 83 (1995), 237-245; Gibbs, Cell 79 (1994), 193-198).
[0019] The present invention further relates to the use of an agent which suppresses the
growth of collateral arteries and/or other arteries from preexisting arteriolar connections
through the attraction of monocytes for the preparation of a pharmaceutical composition
for the treatment of tumors.
[0020] In a preferred embodiment, the agent used in the methods and uses of the invention
as described above inhibits the biological activity of a MCP and/or inhibits an intracellular
signal triggered in the monocytes through the receptor for an MCP, preferably the
aforementioned agent blocks and interaction of the MCP and its receptor. Various receptors
of MCPs are described in the prior art, for example in Charo
68 and Chemokine Receptors
62. Furthermore, it has recently been shown that phosphorylation of the MCP-receptor
mediates receptor desensitization and internalization and that via altering the phosphorylation
sites of the receptor the chemotactic response of leukocytes to MCP-1 and related
chemokines can be modulated
67.
[0021] In another preferred embodiment, said receptor is selected from the group consisting
of CCR1, CCR2, CCR4 and CCR5.
[0022] In a preferred embodiment, the agent which interaction of the MCP and its receptor
is selected from the group consisting of
(i) an anti-MCP antibody and an anti-MCP-receptor antibody; and/or
(ii) a non-stimulatory form of an MCP protein and a soluble form of an MCP-receptor.
[0023] Anti-MCP or MCP-receptor antibodies can be prepared by well known methods using the
purified MCP or its receptor or parts thereof as an antigen.
Monoclonal antibodies can be prepared, for example, by the techniques as described
in Köhler and Milstein, Nature 256 (1975), 495, and Galfré, Meth. Enzymol. 73 (1981),
3, which comprise the fusion of mouse myeloma cells to spleen cells derived from immunized
mammals. Furthermore, antibodies or fragments thereof to the aforementioned MCPs or
their receptors can be obtained by using methods which are described, e.g., in Harlow
and Lane "Antibodies, A Laboratory Manual", CSH Press, Cold Spring Harbour, 1988.
These antibodies may be monoclonal antibodies, polyclonal antibodies or synthetic
antibodies as well as fragments of antibodies, such as Fab, Fv, or scFv fragments
etc.
Non-stimulatory forms of MCPs and antagonists of MCP-receptors have been described,
for example, in Gong
65.
[0024] In another embodiment, the agent which suppresses the growth of collateral arteries
and/or arteriogenesis is an anti-sense RNA of the MCP or of its receptor. It might
be desirable to inactivate the expression of the gene encoding the MCP and/or encoding
its receptor. This can be achieved by using, for example, nucleic acid molecules which
represent or comprise the complementary strand of the mRNA transcript or part thereof
encoding the MCP or its receptor. Such molecules may either be DNA or RNA or a hybrid
thereof. Furthermore, said nucleic acid molecule may contain, for example, thioester
bonds and/or nucleotides analogues, commonly used in oligonucleotide anti-sense approaches.
Said modifications may be useful for the stabilization of the nucleic acid molecule
against endo- and/or exonucleases in the cell. Said nucleic acid molecules may also
be transcribed by an appropriate vector containing a chimeric gene which allows for
the transcription of said nucleic acid molecule in the cell. Such nucleic acid molecules
may further contain ribozyme sequences which specifically cleave the mRNA encoding
the MCP or its receptor. Furthermore, oligonucleotides can be designed which are complementary
to a region of the gene encoding the MCP or its receptor (triple helix; see Lee Nucl.
Acids Res. 6 (1979), 3073; Cooney, Science 241 (1988), 456 and Dervan, Science 251
(1991), 1360), thereby preventing transcription and the production of the MCP or its
receptor.
[0025] In a preferred embodiment, the anti-sense RNA is designed to be expressed in vascular
cells or cells surrounding preexisting arteriolar connections to a tumor.
[0026] In a preferred embodiment, methods and uses of the invention are employed for the
treatment of a tumor which is a vascular tumor, preferably selected from the group
consisting of Colon Carcinoma, Sarcoma, Carcinoma in the breast, Carcinoma in the
head/neck, Mesothelioma, Glioblastoma, Lymphoma and Meningeoma.
[0027] In a preferred embodiment, the pharmaceutical composition in the use of the invention
is designed for administration by catheter intraarterial, intravenous, intraperitoneal
or subcutenous routes. In the examples of the present invention the human form of
the MCP-1 protein was administered locally via osmotic minipump. Positive immunohistochemical
staining for BrdU infused into two animals via the same route as MCP-1 demonstrated
that local delivery of substances into the collateral circulation is feasible.
[0028] The said MCP and its encoding nucleic acid molecule may be used for therapeutical
purposes in various forms. Either as in the experiments described herein, locally
via implanted pumps, or as arterial or venous boluses either systemically or locally
via specially designed catheters or other device. They may also be injected intramuscularly
or into any other tissues in which collateral artery growth needs to be promoted.
Alternatively they can be bound to microcapsules or microspheres before injection.
[0029] Another approach would be to use a gene-transfer approach, either using a plasmid,
or a plasmid embedded in liposomes, or viral vectors. One may either use an in vivo
gene-transfer approach for which multiple devices, like double balloon or other catheters
have been designed or via direct injection into the targeted tissue as described above.
Alternatively it is possible to use an ex vivo approach isolating cells which are
known to lodge in tissues in which vessel growth needs to be promoted or inhibited
from the body which are then transfected using one of the above mentioned methods
and reinjected.
[0030] The use and methods of the invention can be used for the treatment of all kinds of
diseases hitherto unknown as being related to or dependent on the modulation of the
growth of collateral arteries and/or other arteries from preexisting arteriolar connections.
The methods and uses of the present invention may be desirably employed in humans,
although animal treatment is also encompassed by the methods and uses described herein.
[0032] Figure 1: Monocyte/macrophage accumulation after femoral artery occlusion in the rabbit hindlimb.
A) A monocyte adheres to the wall of an excised collateral artery (arrow); two other
macrophages staining green (bright) have already penetrated the vessel wall. B) Macrophages
are also found interstitially in the lower limb (arrows). C) and D) Monocytes/macrophages
staining green (bright) are much more numerous in animals treated with MCP 1 (scale
bars: 20 mm).
[0033] Figure 2: Post-mortem angiograms of rabbit hindlimbs after one week of femoral artery occlusion.
A) Without MCP-1 treatment. B) After one week of local MCP-1 infusion. The density
of collateral vessels with typical corkscrew appearance is markedly increased in hindlimbs
of animals treated with MCP-1.
[0034] Figure 3: A) Staining of bromodeoxyuridine (BrdU) (green (bright) fluorescence) infused continuously
by minipump as proliferation marker and counterstained with phalloidin-TRITC as marker
for actin: Pronounced incorporation of BrdU in endothelial and smooth muscle cells
during the first week of femoral artery occlusion. B) Specific staining of capillaries
with an antibody against CD 31 in a normal gastrocnemial muscle. C) The same muscle
stained for CD 31 after one week of occlusion; the number of capillaries has increased.
D) Gastrocnemial muscle after one week of occlusion and MCP 1 infusion; capillaries
are more numerous after MCP 1 treatment (Scale bars in all pictures: 20 mm).
[0035] Figure 4: Bulk conductance of rabbit hindlimbs after one week of femoral artery occlusion with
local MCP-1 infusion in comparison to control hindlimbs after acute, one week, 3 weeks
or no occlusion. Bulk conductance in animals treated with MCP-1 was significantly
higher than in control animals after the same time of femoral artery occlusion and
reached values of non occluded legs (*p < 0.05 and **p < 0.01 as compared to acute
occlusion; † p < 0.05 as compared to one week of occlusion without MCP-1 treatment).
[0036] Figure 5: Collateral conductance of rabbit hindlimbs after one week of femoral artery occlusion
with local MCP-1 infusion in comparison to control hindlimbs after acute, one week,
and 3 weeks of occlusion in different regions. Collateral conductance in animals treated
with MCP-1 was significantly higher than in control animals after the same time of
femoral artery occlusion in the quadriceps and adductor longus muscle region. These
values tended to be higher than those observed in control animals after three weeks
of femoral artery occlusion (*p < 0.05 and **p < 0.01 as compared to acute occlusion;
†† p < 0.01 as compared to one week of occlusion without MCP-1 treatment).
[0037] Figure 6: Peripheral conductance of rabbit hindlimbs after one week of femoral artery occlusion
with local MCP-1 infusion in comparison to control hindlimbs after acute, one week
and 3 weeks of occlusion. Peripheral conductance in animals treated with MCP-1 was
significantly higher than in control animals after the same time of femoral artery
occlusion. Similar to collateral conductance these values tended to be higher than
those observed in control animals after three weeks of femoral artery occlusion (*p
< 0.05 and **p < 0.01 as compared to acute occlusion; †† p < 0.01 as compared to one
week of occlusion without MCP-1 treatment).
[0038] Figure 7: Number of collateral arteries identified by their stem regions, midzone regions and
reentry regions in stereoscopic, 3-dimensional angiograms. The number of collateral
arteries after one week of occlusion (right leg) was almost twice as high in animal
treated with MCP-1 as compared to animals treated with the carrier alone. No significant
differences were found in the non-occluded left control leg.
[0039] The examples illustrate the invention.
Example 1: Femoral artery occlusion of animals and local delivery of agents
[0040] The present study was performed with permission of the State of Hesse, Regierungspräsidium
Darmstadt, according to § 8 of the German
Law for the Protection of Animals. It conforms with the
Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No.85-23, revised
1985). Twelve rabbits were subjected to 7 days of bilateral femoral artery occlusion.
They were randomly assigned to either receive Monocyte Chemotactic Protein-1 (MCP-1;
PeproTech Inc, Rocky Hill, NJ, USA) locally via osmotic minipump (2ML-2 Alza Corp,
USA; 3 mg in 2 ml phosphate buffered saline (PBS) at a rate of 10 ml/h), PBS via osmotic
minipump or no treatment. Nine additional animals were subjected to either no, acute
or 21 days of femoral artery occlusion for comparison. Two animals were supplied with
an osmotic minipump (2ML-2 Alza Corp, USA) delivering bromodeoxyuridin (BrdU: Sigma
Chemicals, St. Louis) via the same route as MCP-1 to verify the function of the local
delivery system and to study the proliferation of collateral arteries and capillaries.
For the initial surgery the animals were anesthetized with an intramuscular injection
of ketamin hydrochloride (4-8 mg per kilogram body weight) and xylazin (8-9 mg per
kilogram body weight). Supplementary doses of anesthetic (10-20 % of the initial dose)
were given intravenously as needed. Surgery was performed under sterile conditions.
Femoral arteries were exposed and cannulated with a sterile polyethylene catheter
(1 mm i.d., 1.5 mm o.d.) pointing upstream with the tip of the catheter positioned
distally of the branching of the arteria circumflexa femoris. The catheter itself
was connected to the osmotic minipump (2ML-2 Alza Corp, USA) which was implanted under
the skin of the lower abdomen. Rabbits were ouffitted with a specially designed body
suit which allowed them to move freely but prevented selfmutilation. They were housed
together in a large cage with free access to water and chow to secure mobility. Before
sacrifice the animals received another intramuscular injection of ketamin hydrochloride
and xylazin. The animals then underwent tracheostomy and were artificially ventilated.
Anesthesia was deepened with pentobarbital (12 mg/kg bodyweight per hour). The carotid
artery was cannulated for continous pressure monitoring. The arteria saphena magna
(anterior tibial artery in humans; main arterial supply to the lower limb and foot
in the rabbit) was exposed just above the ankle and cannulated with polyethylene tubing
(0.58 mm i.d., 0.96 mm o.d.). They were connected to a Statham P23DC pressure transducer
(Statham, Spectramed, USA) for measurement of pheripheral pressures. After heparinization
with 5000 units of heparin both external iliac arteries were exposed and cannulated
with 2.0 mm bore metal tubing. The abdominal circumflex artery and the arteria spermatica
were ligated and tourniquet placed proximally around both thighs leaving the femoral
artery patent. The femoral and sciatic vein were incised for drainage of venous blood.
The animals then were bled, the legs were amputated above the hip and quickly transferred
to the perfusion apparatus. No animal was lost during or after the primary operation.
It was also not observed any gangrene or gross impairment of function after femoral
artery occlusion. Two animals had to be excluded from the study because of air embolism.
After finishing the experiment all fluid remaining in the reservoir of the minipump
was collected and weighed. In the two control animals receiving bromodesoxyuridine
(BrdU), BrdU staining was performed by standard immunohistochemical methods described
elsewhere
26. Evaluation of fluids remaining in the reservoir revealed that pumping at a rate
of 10 ml/h was accomplished in all experiments. Positive immunohistochemical staining
for BrdU demonstrated that local infusion into the collateral circulation via osmotic
minipump was feasible.
Example 2: Ex vivo pressure-flow relations
[0041] The legs were perfused with autologuous oxygenated blood warmed to 37°C using a Stoeckert
roller pump (Stoeckert GmbH, Germany) and a Jostra M2 membrane oxygenator (Jostra
GmbH, Germany). Hematocrit was kept between 34 % and 37 % and oxygen saturation at
99 %. Maximal vasodilation was achieved by adding 25 mg of papaverine (Sigma Chemicals,
St. Louis USA) to the perfusate (priming volume: 60 ml). The legs were perfused at
three different pressure levels (40, 60 and 80 mmHg). After stabilization radioactive
microspheres were injected and a reference sample drawn using a syringe pump (Braun
Melsung, Germany). For each pressure level microspheres labeled either with Ruthenium,
Cerium and Niobium or Scandium (Dupond NEN Products, USA) were randomly chosen. This
allowed to relate tissue perfusion to different perfusion pressures. Total flow was
determined using an ultrasonic inline flow probe connected to a T201 flowmeter (Transonic
Systems, Inc, USA). Systemic pressures and peripheral capillary pressures were traced
with a Statham P23DC pressure transducer (Statham, Spectramed, USA). All recordings
were transferred online to a computerized recording system (MacLab, Apple Microsoft
USA) from which they were recovered for further processing. Quadriceps, adductor longus
and adductor magnus, gastrocemius, soleus and peroneal muscles were dissected from
the leg and each muscle was divided into five consecutive samples from the proximal
to the distal end. Samples were weighed and subsequently analyzed together with the
respective reference samples using a Ge detector as described previously
27. Of the total 27 hindlimbs which were perfused 4 were excluded because peripheral
presssures could not be obtained and 1 was excluded from the determination of collateral
and capillary conductances because of sampling errors. There were no significant differences
in conductances between animals receiving PBS via minipump and animals receiving no
treatment (bulk conductance: 57.2+/-8.60 vs. 69.2+/-10.01 ; collateral conductance:
24.5+/-5.69 vs. 25.3+/-3.29; all data in ml/min/100mmHg). Therefore these two groups
were combined in the final analysis. For the calculation of sample flows mean sample
activity per gram of muscle weight (A
m/g) was used and related to total flow per gram of muscle weight (F
t/g) which allowed the calculation of sample flow (F
s) using the equation F
s=F
t/A
m x A
s. This correlated well with the calculation of sample flow (F
s) from sample activity (A
s), reference sample activity (A
r), weight of the reference sample (W
r) and time of reference sample withdrawal (t) following the equation F
s=A
s/A
r x W
r/t.
[0042] In the present model collateral arteries developing after femoral artery occlusion
in typical corkscrew formation supply blood to the distal adductor region and the
lower leg. Systemic pressure (SP) and peripheral pressure was used in the saphenous
artery (PP). Venous pressure was equal to atmospheric pressure (AP; zero in the present
case). Since arterial resistances are much lower than collateral and peripheral resistances
they can be neglected. SP represents the pressure at the stem region of the collateral
arteries. PP is the pressure at the reenty region and is identical to the pressure
head of the circulation in the lower leg, AP the pressure at the venous end of the
peripheral circulation. Collateral flow (Fc) is equal to the sum of flow to the tissue
of the distal adductor (FdTA) plus the flow to the tissue of the lower leg (FTII).
(Flow to the bone was very small and the main arterial supply to the foot was ligated.
Therefore these values were neglected in our calculation). Collateral resistance (Rc)
was defined as pressure difference between perfusion pressure (SP) and peripheral
pressure (PP) divided by the flow going to the distal adductor and the lower leg.
Peripheral resistance (Rp) was defined as peripheral pressure (PP) divided by flow
to the lower leg (FTII) and bulk conductance was defined as systemic pressure (SP)
divided by bulk flow recorded with the ultrasonic flow probe. The reciprocal values
of these resistances represent collateral-, peripheral- and bulk conductance (Cc,
Cp and Cb). Because a positive pressure intercept is observed even at maximal vasodilation
all conductances were calculated from the slope of pressure flow relations.
[0043] After one week of femoral artery occlusion bulk conductance as calculated from pressure
flow relations was significantly higher in animals treated with MCP-1 (142.1+/-31.71
ml/min/100mmHg versus 66.2+/-7.76 ml/min/100mmHg; p < 0.05) (Figure 4). After seven
days of occlusion bulk conductances of MCP-1 treated animals reached levels even higher
than in untreated animals after three weeks of femoral artery occlusion and was comparable
to values in non-occluded hindlimbs.
[0044] Collateral conductance also was significantly higher after one week of occlusion
in animals treated with MCP-1 as compared to animals without this treatment ( 70.6+/-19.23
ml/min/100mmHg versus 25.1+/-2.59 ml/min/100mmHg; p < 0.01)(Figure 5). Collateral
conductance of animals that had received MCP-1 for one week tended to be even larger
than in untreated animals after three weeks of femoral artery occlusion in all areas
in which collateral growth was observed. Conductance in the calf also was significantly
higher after one week of femoral artery occlusion in animals with MCP-1 treatment
as compared to rabbits which had not received MCP-1 (119.3+/-22.37 ml/min/100mmHg
versus 45.4+/-6.80 ml/min/100mmHg; p < 0.01) (Figure 6). All data are presented as
mean +/- SEM. Intergroup comparisons were performed by unpaired Student's t-test.
In the case of unequal variances the Mann-Whitney Rank Sum test was used. Probability
values of 0.05 or less were required for assumption of statistical significance.
Treatment with MCP-1 increased both collateral and peripheral conductance 2-fold as
compared to untreated animals after 7 days of femoral artery occlusion. Thus animals
locally injected with MCP-1 reached normal conductance values after one week of occlusion
whereas conductance values in untreated animals did not return to normal levels even
three weeks after occlusion. As mentioned above MCP-1 is mainly known as chemoattractant
for monocytes
31,35. One possible explanation would therefore be that MCP-1 exerts its pronounced effects
on collateral- and peripheral conductance via attraction and activation of monocytes
that in turn produce growth factors which lead to the proliferation of endothelial
and smooth muscle cells. This requires that monocytes adhere to the small arteriolar
connections which are very likely the origin of our collateral arteries
35,48,49. These preexisting arteriolar connections experience a large increase in shear stress
when the main arterial supply to the lower leg is occluded.
Example 3: Post mortem angiography
[0045] After maximal vasodilatation legs were warmed to 37°C and perfused with Krebs Henseleit
buffered saline for one minute followed by perfusion with contrast medium based on
bismuth and gelatine according to a formula developed by Fulton
28. Subsequently the contrast medium was allowed to gel by placing the limb on crushed
ice and angiograms were taken at two different angles in a Balteau radiography apparatus
(Machlett laboratories, USA) using a single enveloped Structurix D7 DW film (AGVA,
Germany). The resulting stereoscopic pictures allowed analysis of collateral growth
in three dimensions.
[0046] Post mortem angiograms exhibited corkscrew collaterals mainly in the adductor longus,
adductor magnus and vastus intermedius muscles connecting the perfusion bed of the
arteria femoralis profunda to that of the arteria saphena parva in the adductor muscles
and the perfusion bed of the arteria circumflexa femoris lateral is to that of the
arteriae genuales in the quadriceps muscle. Angiograms taken from hindlimbs of animals
with MCP-1 treatment showed a remarkable increase in the density of these collateral
vessels (Figure 2 A and B). No collateral vessels were visible on angiograms in the
lower limb of normal and MCP-1 treated animals.
Example 4: Histological studies
[0047] The abdominal aorta was cannulated with a 2 mm bore metal cannula, the chest was
opened and the heart exposed. After incision of the right atrium to allow drainage
of rinsing solution and fixative perfusion was started with a rinsing solution containing
0,5 % BSA, 5 mM EDTA, 0.317 mg/l Adenosin in phosphate buffered saline (PBS) x1.5
for 5 min followed by fixation with formalin 4% in the rinsing solution without BSA
for 20 min. Subsequently a post mortem angiography was performed as described in Example
3. This allowed the precise localization and excision of collateral vessels, their
stem and reentry regions.
For immunohistological studies, samples were kept in 20 % saccharose overnight and
then frozen and mounted on cork in nitrogen cooled methylbutane at -130°C. They were
stored at-80°C until further processing. For visualization of BrdU cryostat sections
of 20 mm were obtained in a Leica CM 3000 cryotom, mounted onto silicone coated slides
and incubated in 2mol/l HCI at 38°C for 20 minutes. After rinsing in PBS 3 times for
5 minutes they were incubated with the primary antibody against BrdU (Clone BU20a,
DAKO Corp.), 1:20 in PBS at 4°C overnight. For detection the samples were incubated
with a biotinylated donkey antimouse antibody (DIANOVA Corp) 1:100 in PBS for one
hour followed by incubation with streptavidin-cy2 (Biotrend, Koeln, Germany) 1:100
in PBS for 30 minutes. Finally sections were counterstained either with 7-aminoactinomycin
D (7-AAD 1:50 in PBS, Molecular Probes, Eugene, Oregon USA) as nuclear stain or phalloidin-TRTC
(1:100 in PBS) as marker for actin. Slides were mounted in Mowiol (Hoechst, Frankfurt/M,
Germany) and viewed by Leica confocal laser microscope. Neighboring sections treated
identically but omitting the primary antibody served as a negative control. Immunohistochemical
staining of capillary endothelial cells was performed following the protocol described
above but with an antibody against CD 31 (DACO, Germany), an endothelial specific
antigen, as primary antibody. Staining for macrophages was performed using RAM 11
(DACO, Germany), a specific antibody against rabbit macrophages as primary antibody.
After femoral artery occlusion monocytes/macrophages were found to accumulate in vessel
walls of excised collateral arteries and intersitially in the lower limb (Figure 1
A and B). They were more numerous in animals treated with MCP-1 (Figure 1 C and D).
Furthermore white plaques were seen macrospically around the infusion site in all
animals receiving MCP-1. These plaques contained large numbers of mononuclear cells
which predominantly were identified as monocytes/macrophages by immunohistochemical
staining with Ram 11 (Dako GmbH, Hamburg, Germany).
By macroscopical inspection of the injection site and histological examination of
collateral arteries from the thigh and tissue sections from calf muscles it became
evident that MCP-1 injection had led to an increase of monocyte accumulation in our
experiment. Positive staining of excised collateral arteries for BrdU provided evidence
that collateral vessels observed on angiography in the thigh were truly proliferating.
[0048] Collateral arteries excised after 7 days of occlusion showed proliferation of endothelial-
and smooth muscle cells on BrdU staining (Figure 3 A). Proliferation of capillary
endothelial cells was seen in the lower limb leading to an increase in the number
of capillaries 7 days after occlusion (Control leg: Figure 3 B; leg after 7 days of
occlusion: Figure 3 C). MCP 1 treated animals showed more capillaries in the lower
limb than untreated animals after a week of occlusion indicating enhancement of capillary
sprouting by MCP 1 (Figure.3 D).
[0049] The immunohistochemical studies after continuous BrdU infusion clearly demonstrated
that collateral vessel formation in the thigh involved proliferation of endothelial-
and smooth muscle cells, given the fact that the normal generation time for endothelial
cells and similar for smooth muscle cells is at least six months and proliferation
is usually not seen in normal arteries
39. The degree of proliferation is similar to that of collateral arteries in the dog
heart after ameroid constrictor placement and approaches that of tumors
40. Although this does not exclude the possibility that MCP-1 enhances collateral artery
proliferation via hypothetical, unrecognized chronic vasodilatory effects, the rapidity
and magnitude of the increase in collateral conductance is far higher than with any
other known vasodilator
41-44. Furthermore monocytes have been shown to downregulate nitric oxide synthase, a very
potent vasodilator, in cultured aortic endothelial cells suggesting that MCP-1 would
rather inhibit than enhance vasodilation
45. Therefore vasodilation is a very unlikely explanation for the above findings. The
higher density of collateral arteries on the angiograms further supports the notion
that collateral artery growth is responsible for the increase in collateral conductance.
In contrast to the thigh were the density of collateral arteries increased, more capillaries
were found in histological sections from calf muscles of MCP-1 treated animals as
compared to control animals after seven days of occlusion. An antibody against CD31(PECAM)
was chosen as marker for endothelial cells because this cell adhesion molecule is
constitutively expressed on all endothelial cells and not dependent on their phenotype
or activation
46,47. Using BrdU as a marker for proliferation only proliferating capillaries in the calf
muscles were detected. No other vessel type was found to grow in this region. As for
collateral conductance passive vessel enlargement due to vasodilation can be excluded
as a reason for peripheral conductance changes by performing the measurements at maximal
vasodilatation. Thus changes in peripheral conductance are most likely attributable
to capillary sprouting.
The histological data suggests that more monocytes accumulate in MCP-1 treated animals.
Since monocytes are potentially capable of producing large amounts of growth factors
this further supports the hypothesis that monocytes are the mediator of the changes
seen with MCP-1 treatment.
In summary, our results have shown that local infusion of MCP-1, a potent and specific
chemoattractant for monocytes, is able to markedly increase collateral- as well as
peripheral conductance. Angiographic and histological findings indicate that this
effect is due to augmented collateral artery- and capillary proliferation and suggest
that adhesion, activation and migration of monocytes play an important role in both
types of vessel growth.
Example 5: Number of collateral arteries
[0050] Post-mortem angiographies were obtained as described in Example 3. For quantification
the bone was extracted and the thigh muscles were unfolded before placing the tissue
in the Balteau radiography apparatus. This allowed the identification and counting
of individual collateral arteries by virtue of their stem regions, midzone regions
and reentry regions on stereoscopic angiograms. The number of collateral arteries
thus counted did not differ in individual animals when obtained independently by four
different observers. Angiograms were obtained from six animals receiving MCP-1 locally
via osmotic minipump after unilateral femoral artery occlusion and compared to angiograms
of six animals receiving the carrier PBS via the same route after femoral artery occlusion.
The results are shown in Figure 7.
[0051] After seven days of occlusion the number of collateral arteries was almost twice
as high in animals receiving MCP-1 as compared to animals receiving PBS alone (30.17+/-1.96
vs 16.17+/-1.4; P < 0.001); see Table 1.
Table 1
PBS I. |
5.00±0.45 |
MCP-1 I. |
6.67±1.17 |
PBS r. |
16.17±1.40 |
MCP-1 r. |
30.17±1.96 |
|
PBS r. vs. MCP-1 r. |
P=0.0002 |
[0052] Table 1: Number of collateral arteries identified by their stem regions, midzone
regions and reentry regions in stereoscopic, 3-dimensional angiograms. The number
of collateral arteries after one week of occlusion (right leg) was almost twice as
high in animal treated with MCP-1 as compared to animals treated with the carrier
alone. No significant differences were found in the non-occluded left control legs.
There was no difference in the number of collateral arteries between MCP-1- and carrier-treated
animals in the non-occluded control legs suggesting that additional mechanisms are
necessary in order to promote collateral growth which are elicited by occlusions.
MCP-1 therefore will not enhance collateral growth or growth of other vessels in sites
without vessel occlusions.
Example 6: Long-term effects of MCP-1 treatment as seen by MRI scanning
[0053] Six animals treated with MCP-1 and 6 control animals were investigated with MRI-scariming
acutely after 7 days, 2 weeks, 1, 2 and 3 months after unilateral femoral artery occlusion.
The anatomical structure was analyzed with highresolution T1-SE Images. MR-angiography
was performed with a 3-D FISP Sequence. Perfusion was measured after an intravenous
bolus of GD-DTPA with a TFL-SR-Sequence. Analysis was performed according to the different
muscle groups. The number of collateral arteries in MCP-1 treated animals was higher
throughout the investigated time frame. In contrast to control animals retrograde
filing of the femoral artery was already normalized after 2 weeks of occlusion in
MCP-1 treated animals.
[0054] In the claims as originally filed there have been disclosed :
(1.) A method for enhancing the growth of collateral arteries and/or other arteries
from preexisting arteriolar connections comprising contacting tissue or cells with
a monocyte chemotactic protein (MCP) or a nucleic acid molecule encoding said MCP;
(2.) Use of a monocyte chemotactic protein (MCP) or a nucleic acid molecule encoding
said MCP for the preparation of a pharmaceutical composition for enhancing collateral
growth of collateral arteries and/or other arteries from preexisting arteriolar connections;
(3.) The method according to item 1 above or the use of item 2 above, wherein said
MCP is selected from the group consisting of MCP-1, MCP-2, MCP-3, MCP-4, MIP-1α, RANTES,
J-309 or any other CC-chemokine or classical chemoattractants like N-farnesyl peptides,
C5a, leukotriene B4 or Platelet-activating factor (PAF);
(4.) The method of item 1 or item 3 above or the use of item 2 or item 3 above for
the treatment of subjects suffering from occlusive diseases;
(5.) The method or the use of item 4 above, wherein the occlusive disease is an arterial
occlusive disease selected from the group consisting of coronary artery diseases,
cerebral occlusive diseases, peripheral occlusive diseases, visceral occlusive diseases,
renal artery diseases and mesenterial arterial insufficiency;
(6.) The method of item 1 or item 3 above or the use of item 2 or item 3 above for
the treatment of subjects during or after exposure to an agent or radiation or surgical
treatment which damage or destroy arteries;
(7.) The method of any one of items 1 or 3 to item 6 above or the use of any one of
items 2 to 6 above, wherein the MCP is a recombinant MCP;
(8.) The use of any one of items 2 to 7 above, wherein the pharmaceutical composition
is designed for administration in conjugation with growth factors like fibroblast
growth factor or vascular endothelial growth factor;
(9.) The method of any one of items 1 or 3 to 7 above, comprising
(a) obtaining cells from a subject;
(b) introducing a nucleic acid molecule encoding the MCP into said cells, thereby
conferring expression and secretion of the MCP in a form suitable for the attraction
of monocytes; and
(c) reintroducing the cells obtained in step (b) into the subject;
(10.) The use of any one of items 2 to 8 above, wherein the nucleic acid molecule
in the pharmaceutical composition is designed for the expression and secretion of
the MCP by cells in vivo in a form suitable for the attraction of monocytes;
(11.) A method for the treatment of tumors comprising contacting tissue or cells with
an agent which suppresses the growth of collateral arteries and/or other arteries
from preexisting arteriolar connections through the attraction of monocytes;
(12.) Use of an agent which suppresses the growth of collateral arteries and/or other
arteries from preexisting arteriolar connections through the attraction of monocytes
for the preparation of a pharmaceutical composition for the treatment of tumors;
(13.) The method of item 11 or the use of item 12 above wherein the agent inhibits
the biological activity of a MCP and/or inhibits an intraceilular signal triggered
in the monocytes through the receptor for a MCP;
(14.) The method or the use of item 13 above, wherein the agent blocks an interaction
of the MCP and its receptor;
(15.) The method or the use of item 14 above, wherein the receptor is selected from
the group consisting of CCR1, CCR2, CCR4 and CCR5;
(16.) The method or the use of items 14 or 15 above, wherein the agent which blocks
an interaction of the MCP and its receptor is selected from the group consisting of
(i) an anti-MCP antibody and an anti-MCP-receptor antibody; and/or
(ii) a non-stimulatory form of an MCP protein and a soluble form of an MCP receptor;
(17.) The method of item 11 or the use of item 12 above, wherein the agent is an antisense
RNA of the MCP or of its receptor;
(18.) The method or the use of item 17 above, wherein the antisense RNA is designed
to be expressed in vascular cells or cells surrounding preexisting arteriolar connections
to a tumor;
(19.) The method of any one of items 11 or 13 to 18 above or the use of any one of
items 12 to 18 above, wherein the tumor is a vascular tumor;
(20.) The method or the use of item 19 above, wherein the tumor is selected form the
group consisting of Colon Carcinoma, Sarcoma, Carcinoma in the breast, Carcinoma in
the head/neck, Mesothelioma, Glioblastoma, Lymphoma and Meningeoma;
(21.) The use of any one of items 2 to 8 or 12 to 20 above, wherein the pharmaceutical
composition is designed for administration by catheter intraarterial, intravenous,
intraperitoneal or subcutaneous routes.
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